Traditionally visually impaired people used a stick to find out if any obstacles are present in front of them and also their approximate distance and position (left, right or in front).
But in present time we can help them by developing a better system using a PIC microcontroller. A PIC microcontroller is small and low cost single chip computer that can do calculations automatically at high speed with great accuracy.
When we combine this power with a pair of ultrasonic wave transmitter and receiver, we can use PIC's accurate time measurement features to measure the time it takes for the sound waves to reach an obstacle and bounce back to the receiver. By quick and fast calculations we can immediately find out the distance in cm. And if the obstacle is too close we can in alert the user with a beep of buzzer and a small vibration of the stick.